Middle English word meaning "conscience" (early 13c.), "reason, intellect" (c.1300), from in (adv.) + wit (n.). Not related to Old English inwit, which meant "deceit." Joyce's use in "Ulysses" (1922), which echoes the 14c. work "Ayenbite of Inwyt," is perhaps the best-known example of the modern use of the word as a conscious archaism.